The present invention relates generally to a motor vehicle seat with an integral child seat and in particular to an energy absorbing child seat.
Special child seats that provide protection for small children in motor vehicles are well known. Two different types of child seats have been developed. One type is a separate seat which is placed upon a vehicle seat and attached thereto by the seat belt provided as part of the vehicle seat. A second type of child seat, commonly referred to as an "integral child seat", has the components of the child seat built into the vehicle seat. Integral child seats typically include one or more movable components which, in one position, enable use of the vehicle seat by an adult, and in a second position, enable use of the vehicle seat by a small child. Common elements of both types of child seats are a lower seat support, a back support and a restraint system for the seat occupant. The restraint system generally includes one or two shoulder belts which are operatively connected between the back support and the seat support to restrain a passenger positioned on the seat support and the back support.
Any vehicle passenger, a child or an adult, can sustain neck injuries when restrained in a seat by a shoulder belt. When the vehicle is involved in a front impact collision, the passengers torso is restrained against the seat back by the shoulder belt while the passenger's head is free to move forward, bending the neck and possibly over extending the neck muscles. In small children, the ratio of the head mass to the body mass is higher than for an adult. As a result, children are somewhat more likely to receive neck injuries in a given vehicle collision. The present invention seeks to reduce neck injuries by providing a flexible mounting of the back panel of the child seat back to the seat structure or frame. The flexible mounting absorbs energy and allows the back panel to move forward relative to the seat frame. The result is a reduced relative velocity and deceleration between the child's head and shoulders, thereby reducing neck loads and injuries.
The present invention employs an air diaphragm to mount the back panel to the seat frame. The diaphragm acts as a shock absorber and extends forward during a frontal vehicle collision allowing the back panel to move forward from the seat frame a limited distance, reducing the deceleration of the seat occupant's head relative to the shoulders. Frangible fasteners are used to mount the back panel to the seat frame and hold the back panel in place during normal seat use. These fasteners hold the back panel substantially rigidly to the seat structure during normal use but are designed to fail at a force below which serious injuries occur, allowing the back panel to move forward under the control of the diaphragm. A tether is attached to the back panel and seat frame to limit the total forward deflection of the back panel.
As the diaphragm extends forward, an enclosed space is formed which increases in size as the diaphragm extends. The rear mounting plate of the diaphragm includes one or more small orifices to limit the flow of air into the enclosed space. The restricted air flow into the space and the elasticity of the diaphragm work together to reduce the deceleration on the seat occupant. Before the diaphragm can return to its unextended position, the air in the enclosed space must first exit through the orifice or orifices. This cushions the return of the back panel and reduces rearward impact on rebound.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.